From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [PATCH net 4/4] tcp: various missing rcu_read_lock around __sk_dst_get Date: Fri, 1 Apr 2016 03:58:48 +0200 Message-ID: <56FDD5D8.2040300@stressinduktion.org> References: <1459466982-20432-1-git-send-email-hannes@stressinduktion.org> <1459466982-20432-5-git-send-email-hannes@stressinduktion.org> <1459467595.6473.233.camel@edumazet-glaptop3.roam.corp.google.com> <56FDBA6E.5030508@stressinduktion.org> <1459469572.6473.239.camel@edumazet-glaptop3.roam.corp.google.com> <56FDBF0E.8020309@stressinduktion.org> <1459473592.6473.243.camel@edumazet-glaptop3.roam.corp.google.com> <1459474618.3751123.565321858.30DF1858@webmail.messagingengine.com> <1459474756.6473.248.camel@edumazet-glaptop3.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org, sasha.levin@oracle.com, daniel@iogearbox.net, alexei.starovoitov@gmail.com, mkubecek@suse.cz To: Eric Dumazet Return-path: Received: from out5-smtp.messagingengine.com ([66.111.4.29]:41485 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752210AbcDAB6x (ORCPT ); Thu, 31 Mar 2016 21:58:53 -0400 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id 948472038A for ; Thu, 31 Mar 2016 21:58:52 -0400 (EDT) In-Reply-To: <1459474756.6473.248.camel@edumazet-glaptop3.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On 01.04.2016 03:39, Eric Dumazet wrote: > On Fri, 2016-04-01 at 03:36 +0200, Hannes Frederic Sowa wrote: >> On Fri, Apr 1, 2016, at 03:19, Eric Dumazet wrote: >>> Thanks. >>> >>> As you can see, release_sock() messes badly lockdep (once your other >>> patches are in ) >>> >>> Once we properly fix release_sock() and/or __release_sock(), all these >>> false positives disappear. >> >> This was a loopback connection. I need to study release_sock and >> __release_sock more as I cannot currently see an issue with the lockdep >> handling. > > Okay, please try : > > diff --git a/net/core/sock.c b/net/core/sock.c > index b67b9aedb230..570dcd91d64e 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -2429,10 +2429,6 @@ EXPORT_SYMBOL(lock_sock_nested); > > void release_sock(struct sock *sk) > { > - /* > - * The sk_lock has mutex_unlock() semantics: > - */ > - mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); > > spin_lock_bh(&sk->sk_lock.slock); > if (sk->sk_backlog.tail) > @@ -2445,6 +2441,10 @@ void release_sock(struct sock *sk) > sk->sk_prot->release_cb(sk); > > sock_release_ownership(sk); > + /* > + * The sk_lock has mutex_unlock() semantics: > + */ > + mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); > if (waitqueue_active(&sk->sk_lock.wq)) > wake_up(&sk->sk_lock.wq); > spin_unlock_bh(&sk->sk_lock.slock); Looks much better with your patch already. I slowly begin to understand, this is really tricky... :) Bye, Hannes